Step motor driving apparatus

Abstract

In a drive apparatus, an operating member is driven by a step motor under control of a control section in response to a signal from a detection section. The control section sets the operating member to an initial position from a mechanically stopped position by forward rotating the step motor at a predetermined step number. At a time of starting an operation of the operating member from the initial position, the control section temporarily reverse rotates the step motor to move the operating member to a detection zone so that the detecting section may detect the signal when the operating member performs a normal movement. Then, the control section responds to the signal to forward rotate the step motor so as to move the operating member to a target position. At a time of a returning operation to the initial position from the target position, the control section reverse rotates the step motor so as to return the operating member from the target position to the detection zone so that the detecting section may detect the signal when the operating member performs a normal movement. Then, the control section responds to the signal to forward rotate the step motor to move the operating member to the initial position, thereby finishing a series of the operations.

What is claimed is:  
     
       1. A method for operating a driving apparatus including a step motor capable of forward rotating and reverse rotating as a drive source, an operating member connected to the step motor for operation from an initial position to a target position, a link member for connecting the operating member to the step motor, a detecting section for detecting a signal when the operating member comes into a detection zone, and a control section for controlling the operating of the operating member by rotating the step motor, comprising the steps of: 
       setting the operating member to the initial position from a mechanically stopped position by forward rotating the step motor at a predetermined step number,  
       temporarily reverse rotating the step motor at a time of starting the operation of the operating member from the initial position to move the operating member to the detection zone so that the detecting section may detect the signal when the operating member performs a normal movement,  
       forward rotating the step motor in response to said signal so as to move the operating member to the target position, and  
       conducting a returning operating to the initial position from the target position by reverse rotating the step motor so as to return the operating member from the target position to the detection zone so that the detecting section may detect the signal, and forward rotate the step motor to move the operating member to the initial position.  
     
     
       2. The method as claimed in  claim 1 , further comprising the step of rotating the step motor so as to forcibly move the operating member to the initial position when the detecting section fails to detect the signal. 
     
     
       3. The method as claimed in  claim 2 , further comprising the step of generating an alarm indicating that an erroneous operation has occurred when the control section fails to forcibly return the operating member to the initial position.